Fiber-optics are steadily replacing copper wire as an appropriate means of communication signal transmission. They span the long distances between local phone systems as well as providing the backbone for many network systems. Other system users include cable television services, university campuses, office buildings, industrial plants, and electric utility companies.
A new market in the fiber optics industry appears to be developing as an alternative to copper or conventional optic links in high-performance computing and data center environments: Active Optical Cables (AOC). As their name implies, the AOCs come with optical transceivers mounted on each end that provide electro-optical (EO) conversion and optical transmission. Users can remove the pluggable copper-based transmission device and plug in the AOC's transceiver/connector, wherein the AOC form factor mirrors that of the copper device it replaces.
To the line card, the active optical cable end looks and functions just like a copper-based transmission device. The fact that the fiber cable comes “hard wired” to the transceiver removes some of the obstacles fiber has encountered in data centers and similar applications. Technicians do not have to worry about eye safety, cleaning, splicing, and other connectorization issues. The AOCs typically include 84% less weight occupying 83% less volume than their copper counterparts. Combined with the natural flexibility of the thinner optical cable, the AOC offers a bend radius 40% less than a 24 AWG copper links. Additionally, the AOCs offer lower latency, indifference to electromagnetic interference, relief from unintended ground loops, price equal to and sometimes better than active copper cables (links that provide amplification and equalization that extend the reach of copper-based transmissions), and a low power interconnect solution because fiber optic is almost lossless compared to a Copper transmission medium with no need for a redriver, buffer chip.
The initial application for active optical cabling is high-performance computing, including cluster computing—applications that have begun to spread from the research and development and scientific communities to high-end enterprise applications for modeling, simulation, and computer-aided design. Passive and active copper cabling provides much of the Infiniband-based server-to-server and server-to-switch connections in such environments. However, as connectivity requirements reach or exceed 10 Gbits/sec and users wish to connect a greater number of more distant computers into clusters, copper's usual bandwidth/distance limitations have become more acute. Industry sources report that passive copper connections begin to sag at around 10 m at 10 Gbits/sec.